Animals are typically branded for identification purposes by applying a very hot iron having the shape of the desired insignia to the hide of the animal until the hair cells are killed and the hide burned or scarred so that hair does not grow in that area. Not only is this technique very painful for the animals, but it permanently damages the hide. Consequently, when the animal is slaughtered, the branded hide has less commercial value than an unblemished hide.
Several years ago it was shown that the hide of an animal can be branded or marked using very cold (i.e., cryogenic) fluids. See, for example, U.S. Pat. No. 3,362,381. The cryogenic fluid may be applied directly to the hide in the desired pattern, or the fluid may be used to reduce the temperature of a suitable iron having the shape of the desired insignia which is then applied to the hide of the animal to be marked. It has been reported that temperatures as high as -30.degree. C. are effective in freeze branding techniques.
When the cryogenic fluid (or an iron cooled by the fluid) is applied to a hide, the pigmentation in the hair and the skin is destroyed. As a result, white hair grows in the area of the applied insignia. The hide itself is not scarred or damaged by the process. Therefore, the hide retains its full commercial value when the animal is slaughtered.
Various types of apparatus have been previously used in freeze branding techniques. U.S. Pat. Nos. 3,515,096; 3,358,648; 3,568,464; 3,411,483; 3,485,060; 3,630,203; 4,531,476; and 4,787,385. U.S. Pat. Nos. 3,421,508 and 3,674,031 describe apparatus for use in cryogenic surgery. However, none of such patents describe freeze branding apparatus having the advantages provided by the present invention.